Doctor



y 5, 1931. F. w. LODDING ET AL 1,803,909

DOCTOR Filed April 2. 1928 rannnnrcx w. ronnrne AND tom w I W EN VEIDDER, 0F WORCESTW, "7: SETTS, ASSIG-NORS TO RICE, BTQN & FALES, HQ'GOREOJPED, 0E WORCESTEK 1m? saonusnr'rs, A CORPORATION or MASSACHUS TTS DOCTOR Application filed April 2, 1928. Serial no. 'a'eaere.

.view of a doctor showing one form of con-' struction which vention.

It is desirable to so construct the doctor blade in contact with the roll, that it will have sufficient longitudinal flexibility to=so may be applied to this inconform its edge as to accommodate itself to any unevenness in the surface of the roll. However, flexibility in the transverse direction is undesirable. In a doctor which is flexible both longitudinally and transversely, the slightest pressure on the doctor causes the blade to turn up on an axis parallel with the roll. The edge is caused to turn upward and provides a wedge wherein paper, grit, et cetera, will tend to force itself and cause the doctor to be ineffective. Another trouble experienced from this condition is-that grit, etc. will get into this wedge-shaped-opening and score the roll, causing considerable damage.

@ui' invention comprises a flexible blade secured in such a manner that its edge will be longitudinally flexible but Will be prevented from bending transversely.

In the drawings we have shown the invention as applied to a rigid doctor back 10 which is employed in connection with the usual roll 11. This doctor back is shown as formed (if an angle iron, but at any rate. it has aportion projecting toward the roll.-

On back at its edge toward -.the roll is fixed, by screws or other means 12, a. holding plate 13 extending to a point near the roll and clamping under it a flexible blade 14, which is adapted to engage the surface of the roll.

Although it will be seen that this blade is flexible, its flexibility operates only in the comparatively narrow space between the edge of the plate 13 and-the roll. It is freeto yield beyond that edge but is held. down at that point at a distance from the doctor back and along a line parallel with the roll and comparatively near it.

- In this way it will be seen that while the flexibility of the blade 14 is taken advantage of to hold the blade against the roll and allow the/blade to bent slightly to accommodate any irregularities in the surface of the roll, it is held from transverse bending and is kept in the same position throughout the length of the roll along a line a short distance from it.

This constitutes a simplification of the ordinary doctor blade, provides for the flexibility of the blade in a lengthwise direction but not transversely and allows for the blade to accommodate itself perfectly to any unevenness of the roll. At the same time it avoids material flexibility in a transverse direction.

The blade is always fixed along the line, at a short distance from the roll, and that does not have to be adjusted after once set up. The importance of backing up the blade back of this line is that it acts as a rigid blade although made of flexible material. Although we have illustrated and described only one form of the invention we are aware of the fact that modifications can be made therein, by any person skilled in the art without departing from the scope of the invention as expressed in the claims.

Therefore, we do not wish to be limited in this respect but what we do claim is i 1. A doctor for the purpose described comprising a rigid support, a flexible blade resting on said support and projecting a material distance beyond it and having an edge parallel with it for engaging the surface to' be operated upon, and a rigid plate secured to said support and bearing on the upper surface of the flexible blade throughout a space extending from the edge of sa1d support. to

be operated u on, and rigid means bearing on the blade yond the extreme edge of said support for preventing the formation of a wedge-like o ening between the blade and the surface to he operated upon.

. 3. The combination with a flexible doctor and a support therefor, of a rigid plate resting on top of it and holding it down all the Way from the edge of said sup ort to a line back of and parallel with its e ge.

In testimony whereof we have hereunto afiixed our signatures.

FREDERICK W. LODDING;

JOHN WARREN VEDDER. 

